Diagnosis: Urticaria
Algorithm for the treatment of chronic urticaria as recommended by the International urticaria medical community. Clinical photograph sourced from Wikimedia Commons (CC BY-SA 4.0). Attribution: Allergyresearch.
Circumscribed, raised, erythematous, edematous plaques (wheals) with surrounding erythema. Individual lesions last <24 hours and resolve without residual marks. May be accompanied by angioedema (deeper tissue swelling).
Acute: identify triggers (foods, medications, infections, insect stings). Chronic: often idiopathic; screen for thyroid disease, infections. Review for pressure, cold, heat, solar, or exercise-induced variants. Assess impact on quality of life.
Acute: second-generation H1 antihistamines (cetirizine, loratadine). Chronic: updosed antihistamines (up to 4x), omalizumab (anti-IgE), cyclosporine. Avoid first-gen antihistamines as first-line. Epinephrine for anaphylaxis.
Urticarial vasculitis, Erythema multiforme, Drug eruption, Mastocytosis, Bullous pemphigoid (pre-bullous), Autoimmune urticaria
Individual wheals lasting >24 hours or leaving bruising suggest urticarial vasculitis — biopsy needed. Omalizumab has transformed management of refractory CSU. Second-generation antihistamines can be safely uptitrated to 4x standard dose.
Tags: urticaria, hives, allergic, mast cell, histamine